A conventional grill device usually includes pivotally-connected upper and lower grilling modules provided respectively with upper and lower grilling plates. A user is required to seta grilling time duration for cooking food disposed between the upper and lower grilling plates. However, determination of the grilling time duration is relatively difficult for a user who has little experience on grilling food. As a result, the food may not be properly cooked when the grill device is operated by an inexperienced user.